package org.apache.solr.search.grouping.distributed.command;

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import org.apache.lucene.search.Collector;
import org.apache.lucene.search.Sort;
import org.apache.lucene.search.grouping.SearchGroup;
import org.apache.lucene.search.grouping.TermFirstPassGroupingCollector;
import org.apache.solr.schema.SchemaField;
import org.apache.solr.search.grouping.Command;

import java.io.IOException;
import java.util.Arrays;
import java.util.Collection;
import java.util.List;

/**
 *
 */
public class SearchGroupsFieldCommand implements
		Command<Collection<SearchGroup<String>>> {

	public static class Builder {

		private SchemaField field;
		private Sort groupSort;
		private Integer topNGroups;

		public Builder setField(SchemaField field) {
			this.field = field;
			return this;
		}

		public Builder setGroupSort(Sort groupSort) {
			this.groupSort = groupSort;
			return this;
		}

		public Builder setTopNGroups(int topNGroups) {
			this.topNGroups = topNGroups;
			return this;
		}

		public SearchGroupsFieldCommand build() {
			if (field == null || groupSort == null || topNGroups == null) {
				throw new IllegalStateException("All fields must be set");
			}

			return new SearchGroupsFieldCommand(field, groupSort, topNGroups);
		}

	}

	private final SchemaField field;
	private final Sort groupSort;
	private final int topNGroups;

	private TermFirstPassGroupingCollector collector;

	private SearchGroupsFieldCommand(SchemaField field, Sort groupSort,
			int topNGroups) {
		this.field = field;
		this.groupSort = groupSort;
		this.topNGroups = topNGroups;
	}

	public List<Collector> create() throws IOException {
		collector = new TermFirstPassGroupingCollector(field.getName(),
				groupSort, topNGroups);
		return Arrays.asList((Collector) collector);
	}

	public Collection<SearchGroup<String>> result() {
		return collector.getTopGroups(0, true);
	}

	public Sort getSortWithinGroup() {
		return null;
	}

	public Sort getGroupSort() {
		return groupSort;
	}

	public String getKey() {
		return field.getName();
	}
}
